Influence of the G2m(n) allotype and age on IgG subclass distribution in antibodies to dietary proteins in children with coeliac disease.

In 47 children with coeliac disease, IgG1 was the dominant IgG subclass (mean 61%) in antibodies to gliadin, a protein component of wheat; IgG2 (22%) and IgG3 (15%) were also found. Very little IgG4 (3%) was detected. Both G2m(n)allotype and the age of the patient had an independent effect on the subclass distribution. The effects of these two factors seem similar to those described earlier on responses to polysaccharides; both G2m(n) and age increase the expression of IgG2 antibodies and concomitantly the share of IgG1 is decreased. The average increase in the share of IgG2 brought about by n/n-genotype was 25.3% (95% confidence limits 12.2-38.4%; P less than 0.001) and that brought about by each additional year of age of the patient 1.1% (0.3-1.9%; P = 0.006). IgG antibodies to beta-lactoglobulin and ovalbumin consisted mainly of IgG1 and IgG4. The titres of the IgG subclasses were low and in many cases below detection level. No association with G2m(n) genotype and share of IgG1 or IgG4 could be demonstrated. Age was inversely correlated with the shares of IgG1 in antibodies to beta-lactoglobulin and ovalbumin.